The present embodiments relate to implantable medical devices and methods, and more particularly to an implantable medical device for the repair of a damaged endoluminal valve, such as an aortic valve, and a method for implanting the same.
The aortic valve functions as a one-way valve between the heart and the rest of the body. Blood is pumped from the left ventricle of the heart, through the aortic valve, and into the aorta, which in turn supplies blood to the body. Between heart contractions the aortic valve closes, preventing blood from flowing backwards into the heart.
Damage to the aortic valve can occur from a congenital defect, the natural aging process, and from infection or scarring. Over time, calcium may build up around the aortic valve causing the valve not to open and close properly. Certain types of damage may cause the valve to “leak,” resulting in “aortic insufficiency” or “aortic regurgitation.” Aortic regurgitation causes extra workload for the heart, and can ultimately result in weakening of the heart muscle and eventual heart failure.
After the aortic valve becomes sufficiently damaged, the valve may need to be replaced to prevent heart failure and death. One current approach involves the use of a balloon-expandable stent to place an artificial valve at the site of the defective aortic valve. Another current approach involves the positioning of an artificial valve at the site of the aortic valve using a self-expanding stent. However, these techniques are imperfect. The normal aortic valve functions well because it is suspended from above through its attachment to the walls of the coronary sinus in between the coronary orifices, and it has leaflets of the perfect size and shape to fill the space in the annulus. These features are difficult to replicate in a percutaneously implanted prosthetic valve. The size of the implantation site depends on the unpredictable effects of the balloon dilation of a heavily calcified native valve and its annulus. Balloon dilation can lead to poor valve function with a persistent gradient or regurgitation through the valve. The diameter of the aortic valve is small and thus the diameter of the dilation is not always predictable, especially with a self-expanding stent. In addition, the shape of the aortic valve is not circular, which can also lead to regurgitation outside the valve.